Fuel conditioning apparatus



Nov. 17, 1931.

F. D. HOFFMAN FUEL CQNDITIONING APPARATUS v Filed Oct. '25. 1928 2 Sheets-Sheet l IllfI-ll brill-tail! IN V EN TOR. 017/770.

ATTORNEY NOV. 17, 1931. I N v 1,831,912

FUEL CONDITIONING APPARATUS Filed Oct. 25. 1928 2 Sheets-Sheet 2 z g nz IN VEN TOR.

' AZTORNEY Patented Nov. 17, 1931 UNITED STATES PATENT OFFICE FRED D. HOFFMAN, OF ST. LOUIS, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

- RICHARD F. KEHR FUEL CONDITIONING AIPARATUS Application filed October 25, 1928. Serial No. 314,997.

My invention relates to furnaces and more particularly to fuel conditioning apparatus therefor, the principal object of the invention being to provide for substantially com- 5, plete combustion of the fuel so as to obtain a maximum number of heat units from the fuel consumed as well as prevent unconsumed gases from passing out of the furnace.

In accomplishing this and other objects I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical sectional view through a furnace equipped with fuel conditioning apparatus constructed according to my invention.

Fig. 2 is a sectional view through the stoker conduit on the line 22, of Fig. 1, illustrating the down draft air inlet.

Fig. 3 is a sectional View through the air preheating device for discharging combustion supporting air into the furnace.

Fig. 4 is a horizontal section through the same taken on the line 44, Fig. 3.

Fig. 5 is a detail sectional view through I the preheater on the line 55, Fig. 4.

Fig. 6 is a bottom plan view of the tuyere plate for the preheater.

Referring in detail to the drawings:

1 designates a furnace which may be of any type but is here illustrated as an ordinary warm air heating furnace including an ash pit 2, grates 3 mounted in a ledge 4 above the ash pit, and a fire bowl 5 encircling the grate and provided at its upper end with the usual radiator 6 for passage of products of combustion to the outlet 7 opening to a chimney (not shown). The ash pit 2 is provided with the usual door 8 for admitting air into the ash pit and through the grates for supporting combustion of the fuel as in ordinary practice.

Positioned in alignment with the fuel door 9 of the furnace is a portable stoker and fuel conditioning apparatus 1.0 including a frame 11 having legs 12 provided with rollers 13, and supported on the frame is fuel grinding apparatus 14 for pulverizing the fuel before it is fed into the furnace.

The grinding apparatus includes a fuel receiving hopper 15, and rotatably mounted in the bottom thereof are fuel crushing rolls 16 for grinding lump fuel contained-in the hopper. Rotatably mounted below the rolls in a conduit 17 extending through the furnace door is a spiral conveyor 18 for feeding fuel pulverized by the rolls into the furnace. 1 he conveyor is driven from a motor 19 carrled by the frame, the motor being connected therewith through a gear reduction unit 20 which carries a drive pinion 21 meshing with a gear 22 fixed on the conveyor shaft. The pulverizing rolls are driven from a gear 23 fixed on the conveyor shaft and which meshes with gears 24 fixed on the roller shafts 25,

The conveyor conduit extends to substantially the center of the furnace andfis provided with a diagonally cut end 27, through which the fuel is discharged into the fire bowl.

In order to provide a down draft over the burning fuel and about the fresh fuel dis charged from the conduit, I provide the conveyor conduit with an outer coaxially mounted conduit 28 spaced therefrom and extending from a point adjacent the outerside of the fuel door to the center of the furnace and provided on its inner end with a downwardly directed outlet 29 for directing air which is admitted about the conveyor conduit downwardly over the fuel on the grate.

In order to control the passage of air through the conduit 28 I provide a bell shaped head 30 on the conduit 28 having an end wall 31 encircling the conveyor conduit and provided with a plurality of openings 32; and to control the effective port area of the openings I provide a ring shaped damper plate 33 having complementary spaced openings 34 so that when the openings in the damper and the conduit are in registration maximum air inlet is provided but when the damper is rotated to move the openings out of registration, the amount of air may be reduced or entirely cut off.

I prefer to control the damper 33 in coniunction with the damper 8 so that when one is open, the other is closed and vice versa, by thermostatic regulation as now described.

A thermostat controlled motor designated the 35 is mounted on a wall of the room to be heated and the motor is provided with an actuating arm 36 connected by a chain 37 with an arm 38 projecting radially from the damper 33. Projecting from the damper diametrically opposite to the arm 38 is an arm 39 connected by a chain 40 with the damper door in the ash pit. Thus when the thermostat raises the arm 38, the damper is rotated to bring the port openings into registration to admit air through the conduit for draft over the fuel, and at the same time the damper 8 is moved to closing position, shutting off draft through the grates.

In order to control the air passing through the grates and preheat the air, and also to permit free passage of a portion of the air through the burning fuel, I provide an air preheating and discharge device 41 com prising a Venturi shaped casting 42 supported concentrically in the furnace and over the grate by an adjustable spider 43. The spider comprises tubular socket members 44 cast integral with the lower bell 45 of the- Venturi shaped member, and slidably mounted in the sockets are arms 46 having downwardly projecting terminals 47 providing foot portions for resting on the flange 4 of the fire bowl. The socket members and the arms are preferably provided with opposite inclined upper walls 48 and 49 so that the fuel will not lodge thereon but will slide off onto the grate. The ridge 50 formed by the inclined walls of the arms are provided with notches 51 and on the inner wall portion of each socket member is an inwardly extending tooth 52 for engaging in the notches of the arms so that when the arms are extended to center the Venturi member the arms will be latched to the socket members and held in ad'usted position thereby.

The arms 46 are urther provided adjacent their rearends with laterally projecting pins 53 and 54 which engage in grooves 55 and 56 formed in the inner sides of the socket members so that when the Venturi member is resting on the flange the pins bear on the lower faces of the grooves and the notched portions of the arms bear against the tooth portions 52 so that the arms are locked in enga ement therewith due to the weight of enturi member "The upper bell 57 of the Venturi member is provided with an inverted cone shaped.

tuyere plate 58 spaced from the periphery of the bell by a plurality of curved blades 59 cast integrally with the plate, and bearing on the top edge thereof, to provide air discharge outlets 60 between the blades. Thus when the upwardly traveling air is gathered by the lower bell and passes through the venturi, the venturi causes the air to expand with substantial velocity into the upper bell and against the tuyere plate where it is directed outwardly. Due to the curved blade,

the, air is discharged through the outlets 50 into the furnace with a whirling motion, thereby thoroughly mixing with rising ases from the fuel bed and causing them to urn before escaping from the furnace.

I have found it desirable to control operation of the stoker conveyor feed according to the room temperature by providing the thermostat 35 with a switch for controlling current to the motor so that when the temperature in the room has reached a desired degree, the thermostat will shut off the motor through an electric circuit 61 to stop feed of the conveyor. i

In operating mechanism constructed and assembled as described, the stoking apparatus may be wheeled to the fuel room and the hopper filled with fuel, or the fuel may be placed in the hopper while the stoking apparatus is in functional relation with the furnace.

The motor may then be started to crush the fuel and feed it into the furnace onto and around theair preheater. The fuel is then ignited, and the draft through the grate'being open, air passes upwardly therethrough to support combustion of the fuel. Part of the air enters the lower bell of the preheater, and passes upwardly through the venturi and out through the outlet 60, as above described, to commingle with-the gaseous products of combustion and promote their combustion, so that said gaseous products will be substantially completely burned before passing out of the furnace.

After the room has become sufficiently warmed, the draft door 8 is automatically lowered and the damper 33 for the down draft is opened by the thermostat to maintain a steady slow burning fire.

I have found that the above described apparatus aids in the complete combustion of the fuel to provide fon economic operation,

1. Incombination with a furnace, and a stoker for discharging fuel into the furnace and having a fuel outlet therein, a Venturi member mounted below the outlet for admitting air to the furnace through the fuel bed, a tuyere plate above the Venturi member for whirling air about the outlet, and a conduit surrounding the fuel outlet for supplying a downdraft in the furnace opposite to the Venturi member.

2. In combination. with a furnace, a stoker for discharging fuel into the furnace, a Venturi member mounted below the fuel dischargaof the stoker for admitting air to the furnace through the fuel 'bed,'a tuyere plate above the Venturi member for whirling air about the fuel disehar e, means for supplying a down draft in the furnace opposite to the first named supply of air, and means for alternately controlling the said air supplies.

3. In combination with a furnace and fuel feedmg means including a conduit extending into the furnace substantially to the center thereof, a Venturi member mounted below the fuel discharge of the fuel feeding conduit for admitting air to the furnace throu h the fuel bed, a tuyere plate above the enturi member for whirling air about the fuel discharge, and means including an air conduit surrounding the fuel feeding conduit and having a downwardly directed outlet for sup-- plying a down draft in the furnace opposite to the Venturi member.

- 4. In combination with a furnace including a fire bowl and a fuel feed door, stoking means including a horizontal conduit extending through the door substantially to the center 2 of the fire bowl, means for admitting air upwardly through a fuel bed in the fire bowl to be discharged concentrically with the fuel discharged from the horizontal conduit, and means including an air supply conduit surrounding the first named conduit and having a downwardly directed outlet surrounding the discharge of the fuel conduit for deliver ing a downdraft around the fuel moving downwardly from the fuel conduit.

5. In combination with a furnace including an ash pit provided with a damper, and stoker mechanism including a fuel conduit extending into the furnace, a conduit for conducting a down draft of air coaxial with said fuel conduit, a damper in said down draft conduit, a Venturi member below the discharge of the fuel conduit for conducting air from the ash pit to the fuel bed, and thermostatically operated means including a chain con- 40 nected with said dampers for coincidently controlling the stoker mechanism and the air supplies.

6. In combination with a furnace including an ash pit provided with a damper, and stoker 5 mechanism including a fuel conduit extending into the furnace, a second conduit for conducting a down draft of air coaxial with said fuel conduit, a damper in said down draft conduit, means below the discharge of the 5 fuel conduit for conducting air from the ash pit through the fuel bed to discharge air above the fuel bed concentric of the down draft, and means for controlling said dampers. I

5 In testimony whereof I aflix my slgnature.

' FRED l). HOFFMAN. 

